If a foreigner is a permanent resident or a citizen, they can buy a house without consequence

However that may come without government subsidies if they are first time homebuyers, but if they are rich and can afford it then it is no problem so long as they are permanent residents or become citizens. However, they are going to be subject to more taxes and regulation than a regular Canadian citizen. If they are on a visa and try to buy a house then you not only ban them from that you also deport them to where they came from. If they are permanent resident or become a Canadian citizen, then a ban is not necessary.